GXT combobox giving JavaScript parent is null errors

Hi,

I have a GXT combobox which I fill up with items, specifically ComboBox<ProjectItem>. When I load my application page the combo box gets properly filled and when I expand it I see the item or items. When I click on these items right away, it gets selected and there's no problem. If, however, I first expand the combo box and then click somewhere else (which I suppose triggers a blur/focus lost event on the combo box) I get the stack trace listed below.

Does anybody have an idea what might be wrong? I instantiate the combo box as follows:

The ProjectItem.PROPERTIES.id() returns a ModelKeyProvider and the label() returns a LabelProvider.

Any help would be highly appreciated!!

Ralph

---------
com.google.gwt.event.shared.UmbrellaException: One or more exceptions caught, see full set in UmbrellaException#getCauses
[ERROR] at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:129)
[ERROR] at com.google.gwt.user.client.Event$NativePreviewEvent.fire(Event.java:87)
[ERROR] at com.google.gwt.user.client.Event$NativePreviewEvent.access$4(Event.java:73)
[ERROR] at com.google.gwt.user.client.Event$.fireNativePreviewEvent(Event.java:488)
[ERROR] at com.google.gwt.user.client.DOM.previewEvent(DOM.java:1328)
[ERROR] at sun.reflect.GeneratedMethodAccessor59.invoke(Unknown Source)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
[ERROR] at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
[ERROR] at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
[ERROR] at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
[ERROR] at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
[ERROR] at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
[ERROR] at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
[ERROR] at sun.reflect.GeneratedMethodAccessor52.invoke(Unknown Source)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
[ERROR] at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
[ERROR] at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
[ERROR] at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
[ERROR] at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
[ERROR] at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
[ERROR] at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
[ERROR] at sun.reflect.GeneratedMethodAccessor52.invoke(Unknown Source)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
[ERROR] at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
[ERROR] at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
[ERROR] at java.lang.Thread.run(Thread.java:680)
[ERROR] Caused by: com.google.gwt.core.client.JavaScriptException: (TypeError): parent is null
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:248)
[ERROR] at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNativeBoolean(ModuleSpace.java:184)
[ERROR] at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeBoolean(JavaScriptHost.java:35)
[ERROR] at com.google.gwt.dom.client.DOMImplMozilla.isOrHasChild(DOMImplMozilla.java)
[ERROR] at com.google.gwt.dom.client.Node$.isOrHasChild$(Node.java:280)
[ERROR] at com.sencha.gxt.cell.core.client.form.ComboBoxCell.collapseIf(ComboBoxCell.java:690)
[ERROR] at com.sencha.gxt.cell.core.client.form.ComboBoxCell$4.onPreview(ComboBoxCell.java:768)
[ERROR] at com.sencha.gxt.core.client.util.BaseEventPreview.onPreviewNativeEvent(BaseEventPreview.java:115)
[ERROR] at com.google.gwt.user.client.Event$NativePreviewEvent.dispatch(Event.java:195)
[ERROR] at com.google.gwt.user.client.Event$NativePreviewEvent.dispatch(Event.java:1)
[ERROR] at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1)
[ERROR] at com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40)
[ERROR] at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193)
[ERROR] at com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88)
[ERROR] at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:127)
[ERROR] at com.google.gwt.user.client.Event$NativePreviewEvent.fire(Event.java:87)
[ERROR] at com.google.gwt.user.client.Event$NativePreviewEvent.access$4(Event.java:73)
[ERROR] at com.google.gwt.user.client.Event$.fireNativePreviewEvent(Event.java:488)
[ERROR] at com.google.gwt.user.client.DOM.previewEvent(DOM.java:1328)
[ERROR] at sun.reflect.GeneratedMethodAccessor59.invoke(Unknown Source)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
[ERROR] at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
[ERROR] at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
[ERROR] at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
[ERROR] at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
[ERROR] at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
[ERROR] at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
[ERROR] at sun.reflect.GeneratedMethodAccessor52.invoke(Unknown Source)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
[ERROR] at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
[ERROR] at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
[ERROR] at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
[ERROR] at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
[ERROR] at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
[ERROR] at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
[ERROR] at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
[ERROR] at sun.reflect.GeneratedMethodAccessor52.invoke(Unknown Source)
[ERROR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[ERROR] at java.lang.reflect.Method.invoke(Method.java:597)
[ERROR] at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
[ERROR] at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
[ERROR] at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
[ERROR] at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
[ERROR] at java.lang.Thread.run(Thread.java:680)